Between 1982 and 1988 the National Heart, Lung, and Blood Institute, the National Institute of Allergy and Infectious Diseases, and the Clinical Center conducted a prospective randomized trial of anti- inflammatory therapy in idiopathic dilated cardiomyopathy. By 1992, after 6 to 9 years of followup, 67 of the 123 patients had died and another 23 had undergone cardiac transplantation. Of the remaining 33 nontransplanted survivors, almost half were asymptomatic. This protocol (93-CC-0096)involves noninvasive followup re-evaluation of these 33 patients, including radionuclide cineangiography, echocardiography, Holter monitoring, and exercise testing. To date, 8 of the 33 patients have been restudied. When completed, this study will represent the first prospective description of the long-term natural history of idiopathic dilated cardiomyopathy in a well-characterized cohort of referral patients. Objective data concerning cardiac size and cardiac function among long-term survivors will permit clinicians to advise newly diagnosed dilated cardiomyopathy patients regarding their prospects for long-term remission.